So this is that dumb au I was talking about a while ago. It's a personality swap au, no one switches places, just prersonalities!

The swaps are as follows:

Sans Undyne | X |Toriel Alphys

Chara Mettaton | X |Asriel Papyrus

Toriel (Sans and Undyne): Very energetic and serious. Loud and upbeat. Still pretty caring though. She pretends not to know a lot, so no one suspects she knows something, that way she stays secure. Pro at karate and puns. Still a big pacifist, that's why she chose karate instead of other martial arts, because karate is mainly for defense, not offense.

Sans (Toriel and Alphys): Shy and timid. Very cautious and caring. Really smart and tries to be funny. Often in his workshop up until late at night, making him take naps often. He helps his brother non stop to achieve maximum popularity.

Papyrus (Mettaton and Chara): Really popular in Snowdin for being so noble and kind. Fashionable and always glad to respond to fan-mail that are usually in need of fashion advice. He's smarter than he seems, often seen reading something in the Librarby. Always on his phone texting and chatting on political and fashion chats. He seems cold, but that's definitely not the case.

Undyne (Toriel and Alphys): A big introvert. Only spends time with close friends and her pet fishies and ducks. Still finishing college, studies oceanography and marine biology. She manages to pass with straight A-s even though she's working hard as a royal guard too. Has a duck army.

Alphys (Sans and Undyne): A big extrovert. Has a lot of friends and is seen on almost every party in the underground. Works as the royal scientist and makes a bunch of little robots for the Royal Guard, she does it to impress the king and Undyne, of course. She's kinda loud and knows how to drive a plane and other aerodynamic vehicles. Wears shades and a lot of clothes because she's an albino. Made Mettaton's body.

Mettaton (Papyrus and Asriel): A big cinnamon roll. Very sweet and shy. His voice is very quiet so it's hard to hear him on his shows. He is still popular, people like him because of how kind and helpful he is. He puts everything else before himself. Very close with Alphys and keeps trying to find ways to make it up to her. A big fan of Papyrus.

Asriel (Mettaton and Chara): He was kind of stuck-up and snotty while alive. He was popular in the entire underground and everyone was always around him and crazy about him. Whatever he said people would instantly agree. It's because of his charisma and wisdom he was so loved and popular. He's very educated and intelligent. Is often mean, but he regrets it, a lot. He has mild depression and insomnia. Often staying up late at night thinking about all the bad things he said and how people will hurt him for it. That's why he has bags under his eyes. Was very close with Chara. He wears a golden heart shaped brooch with a pink gem in it on his tie. Was the one who made the plan and the one who poisoned himself. Still turns into Flowey.

Chara (Papyrus and Asriel): They fell down due to being driven suicidal by bullies at their school for wearing rainbows and for being non-binary. When they climbed the mountain they decided not to jump but they sadly tripped and fell down. They were accepted by the Dreemurrs the way they were and soon they started seeing them as family. Was kind to everybody no matter their looks and views. They wear a locket like Asriel's brooch under their scarf. They often baked pies with Toriel. They decide to follow Asriel's plan and trusted him because they idolized him. They did not turn into a flower but they still died.

I hope you enjoy, if you have ANY questions I will really appreciate them!